Technical Abstract:
To determine the transmissibility of chronic wasting disease (CWD) to fallow deer (Cervus dama) and to provide information about clinical course, lesions and suitability of currently used diagnostic procedures for detection of CWD in this species, 13 fawns were inoculated intracerebrally with CWD brain suspension from elk (n = 6) or white-tailed deer (n = 7). Three other fawns were kept as uninfected controls. This communication documents preliminary observations from a currently in-progress experiment. Three CWD-inoculated deer were euthanized at 7.6 months post inoculation (MPI). None revealed presence of abnormal prion protein (PrP**d) in their tissues. At 24 and 26 MPI one sick deer died and one non-clinical deer was euthanized, respectively. Both animals had a small focal accumulation of PrP**d in their midbrains. Between 29 and 37 MPI, three other deer became sick and were euthanized. All had shown gradual decrease in appetite and some loss of body weight. Microscopic lesions of spongiform encephalopathy were not observed but PrP**d was detected in tissues of the central nervous system by immunohistochemistry, the OIE recommended enrichment Western blot and by two commercial rapid tests. This study demonstrates that intracerebrally inoculated fallow deer amplified CWD PrP**d from white tailed-deer and elk in absence of SE lesions. Similar observations have also been shown to occur in cattle inoculated with the scrapie and CWD agents; however, PrP**d amplification in fallow deer was minimal in comparison to scrapie- and CWD-affected cattle. Four years after the CWD inoculation, the remaining five inoculated and two control deer are alive and apparently healthy. Although these preliminary findings demonstrate that it is possible to transmit CWD to fallow deer by intracerebral inoculation, past experience with TSE cross-species transmission studies indicate a low probability for oral transmission of CWD to fallow deer in the species' normal life span.